It has become increasingly desirable to improve the overall system design and operation of gas turbines. In a system having a typical gas turbine engine, electrical power is extracted via an electrical generator to supply electrical power to control systems, actuators, weapons systems, climate control systems, and the like. Electrical storage, such as a battery, is typically provided to operate such systems when the gas turbine engine is not running or to provide power for starting the gas turbine engine. In some known gas turbine engines, the gas turbine engine includes a high pressure shaft and a lower pressure shaft, and the electrical generator is coupled to one of the high and low pressure shafts.
However, extraction of power from the gas turbine engine via one of the shafts itself typically results in a loss in overall system life, and in particular to the components of the engine to which the electrical generator is coupled. Often, gas turbine systems are designed having redundant components or redundant systems. In one example, a system may include two gas turbine engines so that if one engine fails (or failure is imminent or expected and the engine is thus shut down or in need of maintenance), the other engine may be relied upon for continued safe operation. Such failure may be attributable to a life-limiting component within the failed engine. Although the engine relied upon for continued safe operation may have remaining life and could continue to operate for an extended period of time, its use may nevertheless be limited because the other engine has reached its end of useful life. That is, despite having one engine with possibly a significant amount of remaining useful life, the aircraft is nevertheless grounded for repair.
Further, in such a scenario (one engine, or a component therein, that is life-limited and one having significant remaining useful life), because the one engine is in need of repair, the second engine (though still healthy) may itself undergo repair despite its relative health. In such a case, although the second engine may not need repair, because of the need to repair the one engine, it typically makes sense under such circumstances to conduct repair work on the second engine as well. Or, in another scenario, a first engine may require scheduled maintenance due to a component that is approaching its end of useful life, while the second engine has significant remaining useful life. In such a case as well, although the second engine does not require scheduled maintenance, because of the maintenance on the first engine, it typically makes sense under such circumstances to conduct maintenance on the second engine as well.
In other words, in a two (or multi) engine system, a life-limiting component may force or require action to be taken to repair or perform maintenance on one engine, which can lead to repair or maintenance on a healthy engine as well, and which may be sooner than desired. Thus, the overall life of the system is compromised because if life consumption were better balanced, the overall system would perform for a longer period of time.
Overcoming these concerns would be desirable and could save the industry substantial resources.